Do bacteria ever disappear? New research says yes, bigtime

Despite their ancient history and their omnipresence, the diversity of bacteria remains one of the most cryptic chapters in the history of life. Source: Stilianos Louca, University of British Columbia

According to a new study from the University of British Columbia (UBC), bacteria are disappearing at substantial rates, but seem to avoid massive extinctions that have struck larger forms of life on Earth. , Caltech and Lawrence Berkeley National Laboratory. This discovery contradicts the widespread scientific belief that microbial taxa, because of their very large population, rarely die.

The study, published today in Nature Ecology and Evolution uses massive sequencing and Big Data analysis. to create the first evolutionary tree encompassing much of the Earth's bacteria over the last billion years.

"Bacteria rarely fossilize, so we know very little about how the microbial landscape has evolved over time," says Stilianos Louca. The Biodiversity Research Center of the University of British Columbia who led the study. "Sequencing and mathematics have helped us fill the bacterial tree, map their diversification over time, and discover their extinctions."

Louca and colleagues estimate between 1.4 and 1.9 million bacterial lines on Earth today. They were also able to determine how this number has changed over the last billion years – with 45,000 to 95,000 extinctions in the last one million years only.

"Although modern bacterial diversity is undoubtedly high, evolution has generated on the Earth's history," says Louca.

Stromatolites are some of the few indicators of ancient microbial life. Credit: Woodward Fischer, California Institute of Technology

Despite frequent and regular extinction of individual species, the work shows that, overall, bacteria have diversified exponentially without interruption. And they avoided the abrupt and planetary mass extinctions that occurred periodically in plants and animals. Louca suspects that competition between bacterial species results in high rate of microbial extinctions, leaving them less prone to massive and multi-species extinctions.

Past speciation and extinction events leave a complex trail in the mathematical phylogenies-structures that code evolutionary kinship "This study would not have been possible 10 years ago," says Michael Doebeli University of British Columbia mathematician and zoologist and lead author of this article. "The availability of massive sequencing data and powerful computing resources allowed us to perform complex mathematical analysis."

Next, Louca and his colleagues want to determine how the physiological properties of bacteria evolve over time and whether their ecological diversity also increases similarly to their taxonomic diversity. If this is true, it would mean that even older, relatively simple organisms such as bacteria still have the potential to discover new ways to survive.